As is well known to those skilled in the art, middle distillate fuels typified by diesel oil, Avjet fuel, fuel oils, kerosene, etc. may be stored for extended periods of time under unfavorable conditions which are conducive to formation of solid deposits. These deposits, which are produced during storage at room temperature in the presence of air, accumulate on strainers, filters, screens, etc. with which the oil comes into contact and ultimately plug the openings with resultant problems in operation.
The propensity of a system to form a deposit may be determined by D-2274 which provides indications of oxidative deterioration or stability of a fuel. In the Potential Deposit (PD) Test, comparable indications are obtained under more severe conditions. In this test a test specimen of oil is subject to contact with air at elevated temperature; and after 2 hours, the turbidity of the specimen is determined on a scale of 1-4. A rating of 1 or 2 is satisfactory and a rating of 3 or 4 is unsatisfactory.
It is an object of this invention to provide an improved middle distillate fuel composition characterized by improved performance as determined by the Potential Deposit Test. Other objects will be apparent to those skilled in the art.